Gas lift valve mechanism



Feb. 19, 1963 L. CUMMINGS GAS LIFT VALVE MECHANISM 3 Sheets-Sheet 1 Filed July 21, 1958 LJ/le Z. Cumm/ngw INVENTOR.

A TORNEY iii 94- Feb. 19, 1963 L. CUMMINGS 3,077,894

GAS LIFT VALVE MECHANISM Filed July 21, 1958 3 Sheets-Sheet 2 163//@ L. Cumm/nys INVENTOR. .4

ATTORNEY Feb. 19, 1963 L. CUMMINGS,

GAS LIFT VALVE MECHANISM 3 Sheets-Sheet 3 Filed y 21, 1958 ENTOR.

26 50 I z 5341 w t 7r m fl www.mw w H ,m S T j LeJ/we CUmm/fly senses GAS LL I VALVE MECHANidM Leslie L. Cummings, Houston, Tex, assignor to fltis Engineering @orporation, Dallas, Ten, a corporation of elaware Filed an 21, 195s, Ser. No. 749,812 3 Ciaims. (El. 137-155) This invention relates to well production apparatus and more particularly to gas lift valve mechanism for use in oil wells and the like for controlling the admission of gas under pressure into a column of fluid in the well to assist the outflow of the fluid from the well.

In the production of oil wells it is common practice to provide such wells with a well casing within which a string of tubing or production string of smaller diameter than the casing is positioned and tluough which fluid is removed from the well. Under some conditions, the pressure in the well is insufiicient to cause the well to flow and under these conditions gas lift mechanism is often employed to produce an outflow of well fluid through the tubing.

In the conventional gas lift system gas or air under pressure is introduced into the well casing and is injected through suitable gas-lift valves, located at spaced locations along the tubing, into the column of well fluid inside the tubing to lift the well fluid to the surface. The gas lift valves used for this purpose are constructed and provided with actuating mechanism, whereby the valves are caused to open and close under predetermined pressure conditions in the casing and tubing to control the admission of pressure from the easing into the tubing string.

At times gas lift mechanism is used in wells in which the well bore penetrates oil bearing formations at different depths from which oil may be produced at different rates and under different well pressure conditions. Under these circumstances it is customary to make use of two production strings in the well casing, each of which is arranged to remove the oil from a different formation, this system being commonly 'knownas dual completion.

Gas lift valves, as hereto-fore commonly constructed, do not lend themselves well to accurate adjustment for response to varying well pressure conditions, so that it is extremely ditlicult to adjust the valves throughout the length of the tubing for most economical production. As ordinarily used each valve is separately adjusted before being inserted in the tubing string for operation under the particular pressure conditions which it is expected will be present at the location where the valve will be positioned when the string is inserted in the well, which often results in ineliicient operation when the well is subject to substantial variations in well pressure conditions, or when it becomes necessary to vary the casing pressure to obtain more effective production.

Such gas lift valves are usually constructed for operation by variation in the pressure of fluid in the casing, and valves of this type when used in dual completion operations frequently result in unsatisfactory production because of the wide variation in the pressure conditions in the well where the oil bearing formations are at subs'tantially different depths.

The present invention has for an important object the provision of a gas lift valve actuating mechanism which may be reset for response to widely varying pressure conditions to obtain efiicient production in wells wherein the pressure conditions vary widely.

Another object of the invention is to provide gas lift valve mechanism which is responsive to the pressure in the tubing to open the valve independently of the pressurein the casing.

A further object of the invention is the provision of gas lift valve mechanism embodying valve actuating means which is responsive to the differential of the pressures in the tubing and in the casing, and which may be adjusted for accurate response to a predetermined pressure differential to open or close the valve.

Another object of the invention is the provision of gas lift valve mechanism including valve means which is responsive to the pressure in the casing to close the valve and means operable by the pressure in the tubing when the tubing pressure reaches a predetermined value to cause a reduction in the pressure on the valve to permit the valve to open.

A further object of the invention is to provide gas-lift valve mechanism embodying a valve having actuating means which is responsive to the pressure of fluid in the well casing to hold the valve in closed position and including means for reducing the pressure on said actuating means to allow the valve to open in response to certain predetermined pressure conditions in the well casing and tubing to admit pressure from the casing into the tubing and for reapplying casing pressure to said actuating means to cause the valve to close in response to other predetermined pressure conditions in the casing and tubing.

The above and other important objects of the inven tion may best be understood by the following detailed description, constituting a specification of the same when considered in connection with the annexed drawings, wherein- FIGURE 1 is a diagrammatic View of a portion of a well showing a plurality of the gas lift valves or" the invention installed in a tubing string and illustrating the manner in which the invention is used;

FEGURE 2 is a fragmentary, side elevational view, partly broken away and partly in cross-section, illustrating a preferred embodiment of the gas lift valve of the invention and showingthe valve in open condition;

PlGURE 3 is a view similar to that of FIGURE 2, showing the valve in closed condition;

FIGURE 4 is a fragmentary, vertical, central, crosssectional View, on an enlarged scale, illustrating a preferred embodiment of the pilot valve mechanism of the invention, by which the opening and closing of the gas lift valve is controlled;

FIGURE 5 is a cross-sectional view, taken along the line 5-5 of FIGURE 4, looking in the direction indicated by the arrows;

FIGURE 6 is a fragmentary, vertical, central, crosssectional view illustrating a somewhat modified form of the pilot valve mechanism of FIGURE 4, showing the mechanism in the closed condition of the pilot valve;

FIGURE 7 is a view similar to that of FIGURE '6, showing the pilot valve mechanism of FIGURE 6 with the pilot valve in open condition;

FEGURE 8 is a fragmentary, vertical, central, crosssectional view of a modified form of the pilot valve 'mech anism of the invention showing the pilot valve in open position; and

FIGURE 9 is a view similar to that of FIGURE 8, showing the pilot valve in closed condition.

Referring now to the drawings in greater detail, the invention is illustrated herein in connection with its application to the production of oil from an oil well, such as that illustrated in FIGURE 1, having a bore B in which a well casing C is located which extends into an oil bearing formation F and is provided with perforations P through which well fluid from the formation may enter the casing. The well is provided with the usual production string or tubing T extending downwardly within the casing C and whose lower end is open to permit the outflow of well fluid from the casing through the tubing, and whose upper end extends upwardly through the cas- =3 ing head H closing the upper end in the casing. Suitable packer means S is provided in the Well in position to form a seal between the exterior of the tubing and the interior of the casing at a location above the lower end oi the tubing. T he casing also has a fluid pressure P ply pipe G through which gas under pressure is supp co to connection into the tubing string, e end 1 2 being shown. Adjacent its upper end the b d 12 is provided with a plurality of ports it extendin through the wall of the body and spaced about its circumference and forming gas admission passageways to the tubing string. A tubular housing 18 of somewhat larger diameter than the body 12 is concentrically ranged about the exterior of the body to define an space between the body and the housing forming a valve chamber 2% which enclose the valve mechanism to be subsequently described. The ports it; constitute outlet ports for the valve chamber 2%. The upper end of the housing 18 extends somewhat above ports 16 and valve chamber 2b and is closed at its upper end by a tubular bushing 22, whose up er end is internally threaded for attachment to the externally threaded end 14 of the body. Suitable packer means, such as the 0- ring 24-, positioned in an external groove in the bushing 22, provided for that purpose, forms a seal between the inside of the housing and the exterior of the bushing. The body 12 is also provided with external annular grooves located within the bushing 22, with which suitable packing, such as the G-rings 2d, are located to form a fluid tight seal between the inside of the bushing and the xterior of the body.

The lower end of the valve chamber is closed by means of a closure ring 28 which may be welded or otherwise rigidly connected to the housing 18 and whose inner diameter is somewhat larger than the external diameter of the portion of the body 12, located inside of the closure ring to form an annular passageway 3b in communication with the lower end of the valve chamber in. A lower tubular sleeve 32 surrounds the body 12, which sleeve is connected at its upper end to the closure ring 255, as by means of welding, and at its lower end is similarly connected to an external annular shoulder 34 formed by an annular enlargement 35 on the body. This lower sleeve may have the same external diameter as the housing 15. The sleeve 32 defines the outer wall of an annular diaphragm chamber 36, whose lower end is formed by the shoulder 34 and whose upper end is formed by the closure ring 23.

The lower end of the closure ring 25 has an annular skirt 3% formed with an annular, radially outwardly extending projection 19 on its lower end, about which skirt the upper end of an annular flexible diaphragm extends, which diaphragm is formed with a thickened upper marginal portion 44, positioned above the projection and bonded to the external surface of the skirt 3%. The flexible diaphragm 42 may be formed of a suitable material, such as rubber or the like, and is provided at its lower end with an annular thickened marginal portion 46, which fits into an external annular recess in the body and is bonded to the body in the recess. The lexible diaphragm d2 forms the upper portion of the inner wall of the chamber 36, and separates this chamber from the valve chamber 2b. The external enlargement 35 of the body 12 has a passageway 5b in communication at its upper end with the chamber 36 and whose lower end leads to the exterior of the body, and through which pressure in the casing may enter the chamber to act upon the diaphragm :2.

The upper end of the closure ring 28 is provided with an upwardly extending annular projection 52 of reduced external diameter forming an annular seat 54- bctween the exterior of the projection and the inner wall of the adjacent portion of the housing 18. A main valve 55 which takes the form of a tubular sleeve valve, constructed of flexible resilient material, such as rubber or the like, is coaxially disposed in the valve chamber 2%, surrounding a portion of the body 12. Sleeve valve 56 has a wall thickness substantially less than the width of the chamber 20, and the lower end of the sleeve valve is disposed in the seat 54 and is tightly clamped therein between the outer surface of the projection 52 and the housing 13 to form a fluid tight seal with the housing. At its upper end the sleeve valve is clampingly engaged between the exterior of the body 32 and the inner wall of an internally thickened portion 53 of the housing 18. This internally thickened portion 53 of the housing 13 has one or more passageways 6b, forming a part of the valve chamber 2%. Suitable packing means, such as the O-ring 62, is positioned between the external surface of the body 12 and the internal surface of the thickened portion 58, to form a fluid tight seal therebetween.

The housing is provided with a plurality of peripherally eiongated slots es, extending thercthrough opposite the midportion of the sleeve valve 55 through which presure in the casing may enter the housing. The slots 64 provide communication between the exterior or the housing 18 and valve chamber 2%, being the inlet ports to the valve chamber.

A tubular check valve 66 is mounted in the chamber Ztl surrounding a portion of the body 12 between the ports 16 and the sleeve valve 56. Check valve 66' is composed of flexible resilient material such as rubber, and has an upwardly and outwardly flaring lip portion 68 positioned to be expanded into contact with the internally thickened portion $8 of the housing 18 to close the passageways 69 when the check valve is closed, and which is out of contact with said inwardly thickened portion when the valve is open, to permit the inward flow of fluid through the passageways till through the ports 16. The lower end of the valve as has a thickened portion 79, which is situated between the exterior of the body 12 and the internal wall of the internally thickened portion 58.

The valve chamber 2%) between the valve 56 and the flexible diaphragm d2 is completely filled with a suitable fluid, such as oil or the like, so that upon inward flexing of the diaphragm 42 under the influence of the pressure of fluid entering the chamber 36 from the casing through the passageway 5%, the liquid between the flexible diaphragm and the valve 55 will be forced upwardly to move the valve 56 to closed position, closing the openings 64, as shown in FIGURE 3, to shut oil the flow of gas from the casing into the interior of the tubing through the passageways 60 and ports 16. The flexible diaphragm 42 is so designed that when the pressure in the chamber 36 beneath the diaphragm is the same as the pressure in the casing exteriorly of the chamber the diaphragm will exert a force on the liquid above the diaphragm to hold the valve 56 in closed position as shown in FlGURE 3, or if desired some additional means, such as a spring or the like, not shown, may be positioned about the diaphragm to yieldingly urge the diaphragm toward the body 12, to exert a force on the liquid above the diaphragm to hold the valve 56 closed when the pressure in the chamber 36 is equal to the pressure in the casing exteriorly of the chamber.

Upon a reduction of the pressure in the chamber 36 below the pressure in the casing, which takes place under the control of pilot valve mechanism hereinafter described, the flexible diaphragm 42 will be expanded out wardly, due to the inward pressure of the gas in the casing on the valve 56 through the openings 64 to permit the casing pressure to open the valve 56 to allow fluid to flow from the casing through the passageways 6t) and ports into the tubing.

In the event that the pressure in the tubing should exceed the pressure in the casing, the back flow of fluid through the ports 16 will expand the check valve 66 to close the passageways 66, to prevent such back flow from the tubing into the casing.

Beneath the annular enlargement 35 of the body 12 the body has an annular portion 72 of reduced external diameter, which terminates at its lower end in an external annular enlargement 74 and pilot valve mechanism for controlling the operation of the above described valve 56 is disposed between the annular enlargements 35 and 74, as best seen in FIGURES 4, 5, 8 and 9. The body 12 has a passageway 76 in communication at its inner end with the interior of the tubing, and whose outer end is provided with a valve seat forming a part of such pilot valve mechanism.

A preferred form of the pilot valve mechanism of the invention is illustrated in FIGURES 4 and 5 wherein the valve has a tubular valve casing 78, which may conveniently be made up of a number of tubular sections 34 82 and 84.- which are threadably secured together. The upper end of the uppermost section 8d of the valve casing fits within a downwardly opening recess 36 of the enlargement 3'5 and is provided with an externally threaded upper end or plug 83, threaded into an internally threaded opening in the annular enlargement 35-. The plug 88 is provided with a passageway 92 in communication with the passageways 7s in the body 12, and provides a valve seat 92 within the upper section. The upper end of the upper section 80 is also provided with an annular outwardly flaring end groove 94, into which the lower end of the passageway 5t opens, and from which one or more passageways 96 lead to the interior of the section. The upper section 89 is also provided with a small port 98 in communication with the interior of the section and with the interior of the surroundng casing.

The intermediate section 82 of the casing 78 has an externally threaded upper end portion 1%, which is threadably connected to the internally threaded lower end of the upper section and which substantially closes the same. The upper end of the intermediate section 82 has a central opening therethrough through which a valve stem 162 is slidably extended, which stem carries a valve 164 at its upper end posi ioned to move into and out of closing engagement with the seat 92. The intermediate section 32 also has a side opening 106 therethrough. At its lower end, which is internally threaded, the intermediate section 82 is closed by the externally threaded upper end portion E8 of the lower section 84, and this upper end portion 193 has a central opening therethrough through which the stem 102 is slidably extended into the lower section 84. At its lower end the lower section 34 is closed by a screw plug 11h, which bears against the upper end of a retainer screw 112, which is threadably extended through an opening in the lower annular enlargement 74, to hold the valve casing securely in position on the body 12 and to permit removal of the valve casing therefrom when desired.

An expansible bellows 114 is positioned in the lower section 84, which bellows is attached at its lower end to the plug 110, and at its upper end to a head 116 carried on the lower end of the valve stem 162. The lower section 84 also has a port 118, in communication with the interior of the section and with the interior or" the surrounding casing.

Within the intermediate section 82 a coil spring 120 surrounds the stem 162, which bears at its lower end on the upper end of the lower section 84 and at its upper end against an adjusting nut 122 threadably carried on the stem 102., whereby the force of the spring '12!) exerted on the stem Hi2 tending to move the valve 104 toward closing position may be adjusted.

The lower end plug 11d of the lower section 84 may be provided with an opening 124 closed by a screw plug 126, through which fluid may be introduced into the in terior of the bellows 114.

In the operation of the above described pilot valve mechanism, as best illustrated in FIGURE 4, the bellows 114 is filled with gas at a desired pressure, to urge the valve 1% toward closing position. Due to the fact that the interior of the bellows chamber in the lower section 8 3 is in communication with the interior of the surrounding casing the bellows 1.14 will be subjected to the pressure of fluid in the casing tending to move the valve 1e4- toward open position against the pressure of fluid in the bellows. The valve we will also be urged toward closing position by the spring 12% and also by the upward force exerted on the valve by the pressure of fiuid in the casing entering the upper section 8'9 through the port 98. When the pressure in the interior of the tubing exerted on the valve 1% through the passageways '76 is sufficiently high to coact with the pressure exerted by the fluid in the casing acting on the head 116 of the bellows 114 to overcome the force exerted by the pressure of fluid in the casing acting on the valve 104 in the upper section 118 and the force of the spring 126, then the valve 1% will be opened. Upon opening of the valve 194 fluid may flow from the chamber 36 beneath the flexible diaphragm 42 through passageway 50 and passageways 96 into the upper section 88, and thence through passageways 9i} and 76 into the tubing, so that the pressure of fluid in the casing may enter the housing 18 through openings 64 to move the valve 56 to open position to permit casing pressure to flow into the interior of the tubing through passageways so and ports 16. When the pressure in the tubing falls to a point at which the pressure of the fluid in the bellows 11d and the pre's sure or" the spring 12s are sufiicient to close the valve 194, then the pressure of fluid in the casing will enter the chamber 36 through the port 98, passageways 96 and passageway 5b to act on the diaphragm 42 to exert a force on the liquid above the diaphragm to cause the valve 56 to close, whereupon the inflow of fluid from the casing into the interior of the tubing will be cut oft.

By suitably adjusting the cross-sectional area of the passageway 90, the cross-sectional area of the stem 102, the effective cross-sectional area of the bellows 114 and of the force exerted by the spring 129, the pilot valve 104 may be made to open at any desired differential between the pressure in the casing and tubing.

In gas lift systems of this kind the casing pressure is always maintained substantially higher than the pressure in the tubing, and the port 98 is preferably of very Small diameter so that upon opening of the valve 1% the pressure in the chamber 3%, which will be higher than tubing upon opening of the valve may tubing to permit the valve 56 to be closing of the valve 1% pressure will in the chamber 36 to cause the valve opened, and upon again be built up 56 to close.

Should it be desired to have the pilot valve operated by the pressure in the tubing, independently of the pressure in the casing, then the pressure in the bellows 114 may be adjusted at or near atmospheric pressure and the cross-sectional areas of the passageway 9b and the stem 162. may be made the same, so that the valve will be opened when the pressure in the tubing acting on the valve 1% is suflicient to overcome the pressure of the spring 120.

Suitable means, such as a check valve, not shown, may be installed in the port 98 to prevent back flow from the tubing into the casing.

A somewhat modified form of the pilot valve actuating sermon mechanism of the invention is illustrated in FIGURES 6 and 7, wherein means is provided, such as the leaf spring 12% positioned within the bell ws 114 in position for coaction with the head lie and the plug lit? to maintain the bellows in extended condition, as shown in FF- URE 6 until he pressure exerted on the head 116 by the stem 16?. is sufiicient to cause bending of the spring, as shown in FlGUlZE '7, whereupon the valve will be suddenly moved to open position with a snapping action. By this arrangement the valve 184 will also be moved to closing position by a ction when the pressure on the spring l l is reduced to a point to permit the spring to snap back to its straight position as seen in 6. Other suitable means, such as toggle mechanism or the like, not shown, may of course be substituted for the sprin to cause the quick opening and closing movements of the valve Elli. in other respects the mechanism illustrated in FZGURES 6 and 7 is constructed and operates in the same manner as that previously described in connection with FIGURES 4 and 5.

The stem 1G2 l 3 extended through upper end of the section 02 a portion ltlf; may be of any desired cross-sectional area relative to the cross-sectional area of the passageway 93, the cross-sectional area of the valve lltld am. the crosssectional area of the lower part res of the stern, and these cross-sectional areas may be varied of course as desired to obtain variations in the operating characteristics of the pilot valve.

Assuming that the cross-sectional area of the stern lli'lZ is the same throughout its length and is the same as the cross-sectional area of passageway as, the pressure within the section does not exert any opening or closing action on the valve. With the valve closed tubing pressure is being exerted against the cross-sectional area of the stem and easing pressure is being exerted against the crosssectional area of the bellox 's minus the cross-sectional area of the stem. When the combination of the forces exerted by the tubing and casing pressures exceed the preloaded force of the spring and the bellows tending to close the valve, then the valve will be opened.

When the pilot valve is opened the pressure in chamber as will be reduced and valve as will be opened to allow casing pressure to enter the tubing through openings d4, passageways so and ports 16.

When the combination of casing and tubing pressures falls below the closing forces exerted by the spring and the bellows then the pilot valve will close and the pressure in the section 8% and in chamber 3-5 will be built up to casing pressure thereby closing valve s.

Assuming that the cross-sectional area of the stem portion 103 is smaller than the cross-sectional area of passageway 93, then the pressure in the section will have some effect on the operation of the pilot valve. With the valve closed the forces tending to open the valve will be tubing pressure against the cross-sectional area of passageway 9% plus may have a guide portion the casing pressure against the rim area of head 116. When these combined forces exceed the preloaded forces of the spring and bellows the valve will open, thereby bleeding oil pressure from chamber 35 and permitting valve 56 to open. The forces tending to hold the valve open when the valve is open will be the tubing pressure against the smaller cross-sectional area of portion Hi3 and the casing pressure against the larger rim area of the head 116 and when the combination of these forces falls below the preloaded forces of the spring and bellows then the valve will close allowing pressure to again build up in the chamber 36 to close valve 56.

By making the cross-sectional areas of passageway 99 and the stern portion ltlE both equal to the cross-sectional area of the head 116 (efliective bellows area), the casing pressure will not exert any force on the operation of the pilot valve, and when the tubing pressure against the crosssectional area of the passageway 76 exceeds the closing forces exerted by the bellows and spring the valve will be opened to allow the pressure in chamber 3-5 to bleed off and valve 56 to open. With the valve open when the tubing pressure against the cross-sectional area of the stern falls below the forces of the spring and bellows the valve will be closed and pressure will build up in chamber as to close valve 56.

In FlGURES 8 and 9 there is illustrated a somewhat different embodiment of the pilot valve mechanism of the invention, in which the bellows his is eliminated and a spring 12*? takes the place of the spring 1% previously described. in this arrangement the spring 12% is positioned in the intermedi te section 32 and bears at its upper end on the end portion loll of is section and at its lower end against an adjusting nut 122; threadably carried on the stem luff. and which may be adjusted to regulate the force :rerted by the spri g urging the valve res toward open position. By this arrangement the pilot valve is actuated by the ditlerential of the pressures of fluid in the casing and in the tubin the cross-sectional area ot the stem 162 equal to the cross-sectional area of the passageway id forming the seat for the valve ill the areas acted upon by the tubing pressure and casing pressure may be equalized.

In the form of the invention filustrated in FEGURES 8 and 9, with the valve ltld closed tubing pressure is exerted on the valve against the cross-sectional area of the passageway 9d tending to open the valve, and the spring lid is also exerting a force tending to open the valve. Casing pressure against the cross-sectional area of the passageway fih tends to hold the valve closed. When the combined opening force of the tubing pressure and spring exceeds the closing force of the casing pressure the valve will open to permit bleeding of? of the pressure in chamber 36 and the opening of valve 56. With the valve open, when the pressure in section it against the cross-sectional area of the portion 163 of stern 1G2 and the force of spring lfiztl falls below the force exerted by easing pressure against the stem area, the valve will close to allow pressure to build up in chamber 36 to close valve ss.

By suitably varying the relative cross-sectional area of the passageway )9, valve 1% and stem 162 as well as adjusting the force of the spring 126' the opening and closing characteristics of the pilot valve may be varied as desired.

The gas lift valve mechanism of the invention has been disclosed herein in connection with certain specific embodiments of the same, but it will be understood that this is intended by way of illustration only and that numerous changes can be made in the construction and arrangement of the various parts within the spirit of the invention and the scope of the appended claims.

Having thus clearly shown and described the invention, what is claimed as new and desired to secure by Letters Patent is- 1. Gas lift valve mechanism comprising a tubular body adapted for coaxial connection into a tubing string for insertion with the string into a well casing, an annular valve chamber concentrically surrounding said body and having longitudinally spaced inlet and outlet ports communicating respectively with the interior of said casing and the interior of said body, a tubular valve member constructed of flexible material surrounding the body, said valve member being annularly expansible and contractible to control the passage of fluid through the valve chamber, a pressure chamber surrounding the body ad jacent said valve chamber said valve member forming a common wall between said chambers, an annular diaphragm formed of flexible material in and dividing said pressure chamber to form an upper chamber section between said diaphragm and said valve member and a lower chamber section beneath the diaphragm, a liquid completely filling said up er chamber section, and pilot valve Thus by making means actuated by the pressure of the fluid in the casing and pressure of the fluid in the body for controlling the pressure of fluid in said lower chamber section to cause flexing of said diaphragm to increase and decrease the pressure in said upper chamber section to cause opening and closing movement of said valve member, said valve member preventing passage of fluid through said valve chamber when the pressure within the lower chamber section and the pressure within the interior of said casing are equal.

2. Gas lift valve mechanism comprising a tubular body adapted for coaxial connection into a tubing string for insertion with the string into a well casing, an annular valve chamber concentrically surrounding said body and having longitudinally spaced inlet and outlet ports communicating respectively with the interior of said casing and the interior of said body, a tubular valve member constructed of flexible material surrounding the body, said valve member being aunularly expansible and contractible to control the passage of fluid through the valve chamber, a pressure chamber surrounding the body adjacent said valve chamber said valve member forming a common wall between said chambers, an annular diaphragm formed of flexible material in and dividing said pressure chamber to form an upper chamber Section between said diaphragm and said valve member and a lower chamber section beneath the diaphragm, a liquid completely filling said upper chamber section, means for admitting fluid under pressure from said easing into said lower chamber section to cause said diaphragm to move in one direction to increase the pressure in said upper chamber section to expand the valve element to a position closing ofl flow through said valve chamber, and pilot valve means operated by the pressure of the fluid in the casing and the pressure of the fluid in the body for controlling admission of fluid under pressure from the casing into said lower chamber section and for exhausting the pressure from said lower chamber section to cause said diaphragm to be moved in the other direction by the pressure in said upper chamber section to allow said valve member to contract, said valve element being in said position closing ofi flow through said valve chamber when the pressure within said lower chamber section equals the pressure within the interior of said casing.

3. A gas lift mechanism comprising: a tubular body adapted for coaxial connection into a tubing string for insertion with the string into a well casing; an annular valve chamber concentrically surrounding said body and having longitudinally spaced inlet and outlet ports com- 10 municating respectively with the interior of said casing and the interior of said body; a tubular valve member constructed of flexible material surrounding the body, said valve member being annularly expansible to close said inlet port and contractible to open said inlet port to control the passage of fluid through the valve cham' her; a pressure chamber surrounding the body adjacent said valve chamber, said valve member forming a common wall between said chambers; an annular diaphragm formed of flexible material in and dividing said pressure chamber to form a first chamber section on one side of said diaphragm and between said diaphragm and said valve member and a second chamber section on the other side of said diaphragm; a liquid completely filling said first chamber section; means providing a second valve chamber, a first passage for admitting fluid under pressure from said easing into said second valve chamber, a

second passage communicating said second valve chamber with said lower chamber section and a third passage communicating the interior of said body with said second valve chamber; and pilot valve means operated by the pressure of the fluid in the casing and the pressure of the fluid in the body for controlling flow through said third passage, said diaphragm being moved in one direction when fluid under pressure from the casing is admitted into said second chamber section to increase the pressure in said first chamber section to expand said valve member to close said inlet port, said third passage having a larger orifice than said first passage whereby when said pilot valve means is in open position permitting fluid flow through said third passage the pressure from said lower chamber section is exhausted to the interior of said body through said second passage, said second valve chamber and said third passage to cause said diaphragm to be moved in the other direction by the pressure in said first chamber section to allow said valve member to contract to open said inlet port, said valve member being expanded to close said inlet port when the pressure in said second chamber section is equal to the pressure within the interior of said casing.

References Cited in the file of this patent UNITED STATES PATENTS 2,325,264 Merten July 27, 1943 2,391,605 Walton Dec. 25, 1945 2,446,630 Walton Aug. 10, 1948 2,620,740 Garrett Dec. 9, 1952 2,642,889 Cummings June 23, 1953 

1. GAS LIFT VALVE MECHANISM COMPRISING A TUBULAR BODY ADAPTED FOR COAXIAL CONNECTION INTO A TUBING STRING FOR INSERTION WITH THE STRING INTO A WELL CASING, AN ANNULAR VALVE CHAMBER CONCENTRICALLY SURROUNDING SAID BODY AND HAVING LONGITUDINALLY SPACED INLET AND OUTLET PORTS COMMUNICATING RESPECTIVELY WITH THE INTERIOR OF SAID CASING AND THE INTERIOR OF SAID BODY, A TUBULAR VALVE MEMBER CONSTRUCTED OF FLEXIBLE MATERIAL SURROUNDING THE BODY, SAID VALVE MEMBER BEING ANNULARLY EXPANSIBLE AND CONTRACTIBLE TO CONTROL THE PASSAGE OF FLUID THROUGH THE VALVE CHAMBER, A PRESSURE CHAMBER SURROUNDING THE BODY ADJACENT SAID VALVE CHAMBER SAID VALVE MEMBER FORMING A COMMON WALL BETWEEN SAID CHAMBERS, AN ANNULAR DIAPHRAGM FORMED OF FLEXIBLE MATERIAL IN AND DIVIDING SAID PRESSURE CHAMBER TO FORM AN UPPER CHAMBER SECTION BETWEEN SAID DIAPHRAGM AND SAID VALVE MEMBER AND A LOWER CHAMBER SECTION BENEATH THE DIAPHRAGM, A LIQUID COMPLETELY FILLING SAID UPPER CHAMBER SECTION, AND PILOT VALVE MEANS ACTUATED BY THE PRESSURE OF THE FLUID IN THE CASING AND PRESSURE OF THE FLUID IN THE BODY FOR CONTROLLING THE PRESSURE OF FLUID IN SAID LOWER CHAMBER SECTION TO CAUSE FLEXING OF SAID DIAPHRAGM TO INCREASE AND DECREASE THE PRESSURE IN SAID UPPER CHAMBER SECTION TO CAUSE OPENING AND CLOSING MOVEMENT OF SAID VALVE MEMBER, SAID VALVE MEMBER PREVENTING PASSAGE OF FLUID THROUGH SAID VALVE CHAMBER WHEN THE PRESSURE WITHIN THE LOWER CHAMBER SECTION AND THE PRESSURE WITHIN THE INTERIOR OF SAID CASING ARE EQUAL. 